Development of a biocompatible hermetically sealed electrical feedthrough

A new biocompatible hermetically sealed electric wire feedthrough has been developed for use in a totally implantable artificial heart (TAH) and ventricular assist device (VAD). This feedthrough allows electric current to pass through a rigid polyurethane (Isoplast 301, Dow Chemical U.S.A., Midland, MI) housing wall. The implantable housing is exposed externally to tissue and body fluids and is filled with low viscosity silicone oil (decamethyltetrasiloxane) which acts as a hydraulic fluid. The feedthrough prevents fluid transfer which caused early prototype devices to fail. The feedthrough consists of external and internal wires insulated with soft segmented polyurethane (Biomer, Ethicon, Somerville, NJ) and soldered to opposite ends of a conductive pin. The pin and the wire connections are encapsulated in Biomer, forming a leak-free barrier between the housing wall and the wire insulation. The pin soldered between the two wires prevents leakage from between the strands and the insulation.